Chemistry 1 (Objective) & Chemistry 2 (Essay) – WAEC 2025 Complete Guide
Introduction
Understanding WAEC Chemistry Papers
Chemistry is a core science subject in the WAEC examination. It plays a critical role in science-related courses like medicine, pharmacy, engineering, and biochemistry. To evaluate students' grasp of this subject, WAEC divides Chemistry into three papers:
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Paper 1 – Objective (Multiple Choice)
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Paper 2 – Essay (Theory and Calculations)
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Paper 3 – Practical (covered in a separate article)
This article focuses on Paper 1 and Paper 2, guiding you on what to expect and how to prepare effectively.
The Importance of Paper 1 and Paper 2 in Chemistry
Chemistry Paper 1 tests your speed and precision across a wide range of topics using 50 multiple-choice questions. Paper 2, on the other hand, evaluates your deep understanding, problem-solving skills, and ability to explain, draw, and calculate in essay form.
To pass Chemistry, and even aim for distinctions, you need to perform well in both papers. Scoring high in Paper 1 provides a strong foundation, while Paper 2 allows you to show in-depth knowledge and earn more marks through structured answers.
WAEC 2025 Chemistry Paper Structure
Paper 1 – Objective Overview
This section includes 50 multiple-choice questions from all areas of the syllabus. You must answer all within 1 hour.
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Marks: 50 marks
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Question Style: Direct questions with four options (A–D)
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Topics Covered:
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Atomic structure
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Periodic table
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Organic and inorganic chemistry
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Calculations
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Chemical bonding
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Electrolysis
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Acids, bases, and salts
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Gas laws
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Paper 2 – Essay and Theory Format
This paper tests your comprehensive understanding and reasoning in Chemistry. It includes 2 sections:
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Section A – Compulsory: Usually contains short-answer and calculation-based questions.
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Section B – Choose any four questions out of five: These are essay-type questions with parts (a, b, c…).
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Duration: 2 hours
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Marks: 100 marks total
Marks Breakdown:
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Section A: 25 marks
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Section B: 4 questions x 20 marks = 80 marks
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Neatness, correct units, and logical steps in calculations are essential.
Chemistry 1 (Objective): Key Topics and Question Style
Common Areas Covered in MCQs
To succeed in Paper 1, you should revise:
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Atomic structure – protons, electrons, neutrons
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Periodic table – groups, periods, trends
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Chemical bonding – covalent, ionic, metallic
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Acids and bases – pH, indicators, reactions
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Gas laws – Boyle’s law, Charles’ law, ideal gas law
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Chemical equations and mole concept
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Organic chemistry basics – hydrocarbons, isomerism
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Electrolysis – electrochemical cells, electrodes
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Chemical kinetics and equilibria
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Separation techniques – filtration, distillation
Sample Objective Questions with Answers
1. The number of neutrons in an atom of mass number 23 and atomic number 11 is:
A. 11
B. 12
C. 23
D. 34
Answer: B. 12
Explanation: Neutrons = Mass number – Atomic number = 23 – 11 = 12
2. Which of the following is a noble gas?
A. Nitrogen
B. Oxygen
C. Argon
D. Carbon dioxide
Answer: C. Argon
Explanation: Noble gases are in Group 18; Argon is one of them.
3. A covalent bond is formed by:
A. Transfer of electrons
B. Sharing of electrons
C. Loss of protons
D. Sharing of neutrons
Answer: B. Sharing of electrons
4. Which gas law relates pressure and volume?
A. Boyle’s Law
B. Charles’ Law
C. Dalton’s Law
D. Graham’s Law
Answer: A. Boyle’s Law
5. A solution with pH 2 is:
A. Strongly acidic
B. Weakly acidic
C. Neutral
D. Alkaline
Answer: A. Strongly acidic
Chemistry 2 (Essay): What to Expect
Types of Questions Asked
WAEC Chemistry Paper 2 includes:
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Definition and explanation of concepts (e.g., types of bonds)
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Balanced chemical equations
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Problem-solving/calculations (e.g., titration, moles)
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Drawing and labeling diagrams (e.g., electrolysis setup)
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Comparison and trend explanation (e.g., atomic radius across periods)
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Organic chemistry reaction mechanisms
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Reasoning questions (e.g., why metals conduct electricity)
How to Structure Essay Answers
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Begin with definitions if the question includes technical terms.
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State formulas clearly when doing calculations.
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Show full working – Marks are awarded for steps, not just the final answer.
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Use correct units – Always include mol, dm³, g/mol, etc.
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Use bullets for listing – Makes points clear.
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Underlining keywords like “exothermic,” “oxidation,” “polymerization” adds clarity.
Pro tip: Label your diagrams and write neatly. Use subheadings if necessary for longer answers.
WAEC 2025 Likely Chemistry Essay Questions
Sample Questions and Answers
Question 1:
Define the mole and calculate the number of moles in 22 grams of CO₂ (Molar mass = 44 g/mol).
Answer:
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Mole is the amount of substance that contains as many particles as there are atoms in 12 grams of carbon-12.
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Moles = Mass / Molar mass = 22 / 44 = 0.5 moles
Question 2:
Describe the electrolysis of acidified water and write the half-cell equations.
Answer:
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Electrolysis splits water into hydrogen and oxygen gases.
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At cathode: 2H++2e−→H2(g)
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At anode: 2H2O→O2(g)+4H++4e−
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Oxygen is collected at the anode, and hydrogen at the cathode.
Question 3:
State three characteristics of transition elements.
Answer:
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They form colored compounds.
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They have variable oxidation states.
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They act as catalysts in chemical reactions.
Chemistry Equations and Calculations
Balancing Equations
Balancing chemical equations is essential in WAEC Chemistry Paper 2. Questions usually require students to:
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Identify reactants and products
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Balance atoms on both sides of the equation
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State physical states (solid, liquid, gas, aqueous)
Example:
Balance the equation:
Balanced Equation:
2Na+2H2O→2NaOH+H2Tips:
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Start by balancing metals.
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Then balance hydrogen and oxygen last.
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Use coefficients (not subscripts) to balance.
Moles, Molarity, and Titration Calculations
These topics appear regularly in Section A of the essay paper. Mastery of formulas is key.
Formulas to Remember:
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Moles (n) = Mass (g) / Molar Mass (g/mol)
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Molarity (M) = Moles / Volume (dm³)
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Titration Formula:
(where C is concentration, V is volume)
Sample Question:
Calculate the number of moles in 250 cm³ of 0.2 M NaOH.
Solution:
Convert cm³ to dm³: 250 cm³ = 0.25 dm³
Moles = Molarity × Volume = 0.2 × 0.25 = 0.05 mol
Key Tip: Always convert volume to dm³ (1 dm³ = 1000 cm³).
Organic Chemistry in WAEC
Functional Groups and Reactions
You are expected to:
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Identify functional groups (alcohols, carboxylic acids, alkanes, alkenes)
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Recognize chemical reactions like substitution, addition, and esterification
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Draw structural and molecular formulas
Examples of Functional Groups:
Group | Example | Functional Group |
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Alcohol | Ethanol | -OH |
Alkene | Ethene | C=C |
Carboxylic Acid | Ethanoic acid | -COOH |
Ester | Ethyl ethanoate | -COO- |
Common Reactions Tested:
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Addition: Alkene + H₂ → Alkane
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Esterification: Alcohol + Acid → Ester + Water
Question Example:
Write an equation for the reaction between ethanol and ethanoic acid.
Answer:
CH3COOH+C2H5OH→CH3COOC2H5+H2ONomenclature and Isomerism
Students must know how to name organic compounds and recognize different isomers.
Example:
Draw two isomers of C₄H₁₀.
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Butane (straight chain)
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Methylpropane (branched)
Also, understand functional group isomerism (e.g., alcohol vs. ether) and chain isomerism (straight vs. branched chains).
Inorganic Chemistry Essentials
Periodic Table Trends
You will be asked to describe and explain:
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Atomic radius trend across a period and down a group
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Ionization energy trend
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Electronegativity
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Metallic and non-metallic character
Sample Essay Question:
Explain why atomic radius decreases across a period.
Answer:
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Nuclear charge increases while shielding remains constant.
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Electrons are pulled closer to the nucleus.
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Hence, atomic size decreases.
Group Properties:
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Group I: Alkali metals – reactive, soft, low melting points
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Group VII: Halogens – form salts, diatomic, colored vapors
Transition Elements:
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Form colored compounds
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Exhibit variable oxidation states
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Are good catalysts (e.g., Fe in Haber process)
Physical Chemistry Fundamentals
Gas Laws and Energetics
Be able to explain and apply:
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Boyle’s Law: P ∝ 1/V
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Charles’ Law: V ∝ T
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Ideal Gas Law: PV = nRT
Sample Calculation:
A gas occupies 2 dm³ at 100 kPa. What is its volume at 200 kPa (temperature constant)?
Solution:
P₁V₁ = P₂V₂
(100)(2) = (200)(V₂)
V₂ = 0.5 dm³
Energetics:
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Define exothermic and endothermic reactions
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Draw energy profile diagrams
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Calculate enthalpy change (ΔH)
Chemical Equilibrium and Kinetics
Equilibrium:
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State Le Chatelier’s Principle
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Predict effects of temperature, pressure, and concentration
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Write equilibrium expressions
Kinetics:
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Define activation energy and catalysts
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Draw reaction rate graphs
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Explain collision theory
Diagrams and Graphs in Chemistry Essay
Energy Profile Diagrams
You must draw and interpret diagrams for:
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Exothermic and endothermic reactions
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Activation energy
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ΔH (enthalpy change)
Graphical Data Interpretation
You may be asked to:
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Analyze temperature vs. reaction rate graphs
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Interpret pH vs. time during titration
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Read solubility curves
Ensure all graphs have:
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Title
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Labeled axes with units
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Smooth curves or straight lines
Tips to Excel in WAEC Chemistry Papers
Time Management
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Spend 1 minute per objective question in Paper 1
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Allocate 25–30 minutes per essay in Paper 2
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Use last 10 minutes to revise and correct units or formulas
Flashcards and Formula Sheets
Create flashcards for:
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Functional groups
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Gas laws
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Periodic trends
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Common equations and definitions
Stick a formula sheet to your wall or notebook for daily reference.
Past Question Practice and Mock Tests
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Solve at least 3–5 past essay questions per week
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Practice under exam conditions
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Have your answers marked by teachers or senior students
Conclusion
WAEC Chemistry Papers 1 and 2 demand a balanced approach—speed and accuracy for Paper 1, and depth of understanding and clarity for Paper 2. Whether you’re calculating moles, drawing energy diagrams, or explaining periodic trends, a solid study routine and disciplined practice are the keys to success.
Focus on high-yield topics like mole concepts, equations, organic chemistry, and gas laws. Use flashcards, practice diagrams, and revise with past questions. Chemistry isn’t just about memory—it’s about logic, application, and smart learning.
FAQs
1. How many questions are in WAEC Chemistry Paper 1?
Paper 1 consists of 50 multiple-choice questions, and you must answer all within 1 hour.
2. Are calculations important in the essay paper?
Yes. Calculation questions on moles, titration, gas laws, and energetics are regularly tested in Section A and are usually compulsory.
3. How do I revise for Chemistry effectively?
Use flashcards, practice past questions, draw diagrams, and review formulas daily. Study in chunks and review weak topics more often.
4. What topics are frequently repeated in Chemistry WAEC?
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Mole concept
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Organic reactions
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Electrolysis
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Acid-base titration
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Periodic trends
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Energy changes
5. Can I bring a calculator for the exam?
Yes. Non-programmable scientific calculators are allowed and necessary for calculations.
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